US20240408909A1 - Recording medium, card, and booklet - Google Patents

Recording medium, card, and booklet Download PDF

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Publication number
US20240408909A1
US20240408909A1 US18/689,766 US202218689766A US2024408909A1 US 20240408909 A1 US20240408909 A1 US 20240408909A1 US 202218689766 A US202218689766 A US 202218689766A US 2024408909 A1 US2024408909 A1 US 2024408909A1
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United States
Prior art keywords
recording medium
formula
group
layer
recording
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US18/689,766
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English (en)
Inventor
Yuriko Kaino
Kenichi Kurihara
Ayumi KAI
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Sony Group Corp
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Sony Group Corp
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Publication of US20240408909A1 publication Critical patent/US20240408909A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/333—Colour developing components therefor, e.g. acidic compounds
    • B41M5/3333—Non-macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/40—Manufacture
    • B42D25/405—Marking
    • B42D25/41—Marking using electromagnetic radiation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
    • B41M2205/04—Direct thermal recording [DTR]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
    • B41M5/337—Additives; Binders
    • B41M5/3372—Macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/34—Multicolour thermography
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
    • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
    • B41M5/46—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography characterised by the light-to-heat converting means; characterised by the heat or radiation filtering or absorbing means or layers

Definitions

  • the present disclosure relates to a recording medium, a card including the same, and a booklet.
  • Patent Literature 1 describes using a bis(hydroxybenzoic acid) compound (bisurea compound) represented by a specific formula as a color developer.
  • Patent Literature 1 does not consider color development retention characteristics in a high-temperature and high-humidity environment.
  • a first disclosure is a recording medium, including:
  • a second disclosure is a recording medium, including:
  • a third disclosure is a card including the recording medium according to the first or second disclosure.
  • a fourth disclosure is a booklet including the recording medium according to the first or second disclosure.
  • FIG. 1 is a cross-sectional view showing an example of a configuration of a recording medium according to a first embodiment.
  • FIG. 2 is a cross-sectional view showing an example of a configuration of a recording medium according to a second embodiment.
  • FIG. 3 is a cross-sectional view showing an example of a configuration of a recording medium according to a third embodiment.
  • FIG. 4 is a perspective view showing an example of a configuration of a stacked body according to a fourth embodiment.
  • FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4 .
  • FIG. 6 is a cross-sectional view showing an example of a configuration of a stacked body according to a fifth embodiment.
  • FIG. 7 Part A of FIG. 7 is a plan view showing an example of the appearance of an application example 1.
  • Part B of FIG. 7 is a cross-sectional view taken along the line VIIB-VIIB in Part A of FIG. 7 .
  • FIG. 8 is a perspective view showing an example of the appearance of an application example 2.
  • FIG. 9 Part A of FIG. 9 is a plan view showing an example of the appearance (front surface side) of an application example 3.
  • Part B of FIG. 9 is a plan view showing an example of the appearance (back surface side) of the application example 3.
  • FIG. 10 Part A of FIG. 10 is a plan view showing an example of the appearance (front surface side) of an application example 4.
  • Part B of FIG. 10 is a plan view showing an example of the appearance (back surface side) of the application example 4.
  • FIG. 11 Part A of FIG. 11 is a perspective view showing an example of the appearance (front surface side) of an application example 5.
  • Part B of FIG. 11 is a perspective view showing an example of the appearance (back surface side) of the application example 5.
  • FIG. 12 Part A of FIG. 12 is a plan view showing an example of the appearance (first surface side) of an application example 6.
  • Part B of FIG. 12 is a plan view showing an example of the appearance (second surface side) of the application example 6.
  • FIG. 13 Part A of FIG. 13 is a plan view showing an example of the appearance (top surface side) of an application example 7.
  • Part B of FIG. 13 is a plan view showing an example of the appearance (side surface side) of the application example 7.
  • FIG. 14 is a plan view showing an example of the appearance of an application example 8.
  • FIG. 15 is a perspective view showing an example of the appearance of an application example 9.
  • FIG. 16 Part A of FIG. 16 is a plan view showing an example of the appearance of an application example 10.
  • Part B of FIG. 16 is a cross-sectional view taken along the line XVIB-XVIB in Part A of FIG. 16 .
  • the recording medium 10 is configured such that its coloring state can be changed by irradiation of laser light (external stimulation). By using the change in coloring state, an image or the like can be drawn on the recording medium 10 .
  • the image includes not only an image such as a design, a color pattern, and a photograph, but also a text such as a character and a symbol.
  • the laser light is favorably near-infrared laser light.
  • the change in coloring state may be a reversible change or an irreversible change. That is, the recording medium 10 may be rewritable, in which an image or the like can be rewritten, or write-once, in which an image or the like can be written only once. From the viewpoint of anti-tamper properties, the change in coloring state is favorably an irreversible change.
  • the recording medium 10 includes a base material 11 and a recording layer 12 provided on the base material 11 .
  • the recording medium 10 may further include a protective layer 13 provided on the recording layer 12 .
  • the base material 11 , the recording layer 12 , and the protective layer 13 will be described in order.
  • the base material 11 is a support for supporting the recording layer 12 .
  • the base material 11 is favorably formed of a material having excellent heat resistance and excellent dimension stability in the planar direction.
  • the base material 11 may have either optical transparency or non-optical transparency.
  • the base material 11 may have a predetermined color such as white.
  • the base material 11 has, for example, a plate shape or a film shape. In the present disclosure, the film is defined to include a sheet.
  • the base material 11 may have, for example, rigidity or flexibility. In the case where the base material 11 having flexibility is used, it is possible to realize a flexible recording medium 10 .
  • Examples of the base material 11 having rigidity include a wafer and a glass substrate.
  • Examples of the base material 11 having flexibility include flexible glass, a film, and paper.
  • Examples of the constituent material of the base material 11 include an inorganic material, a metal material, and a polymer material. Two or more of the inorganic material, the metal material, the polymer material, and the like may be combined. In the case where two or more constituent materials are combined, the two or more constituent materials may be stacked. In the case where an inorganic material and a polymer material are combined, particles of the inorganic material may be dispersed and contained in the polymer film. Similarly, also in the case where a metal material and a polymer material are combined, particles of the metal material may be dispersed and contained in the polymer film.
  • the inorganic material includes, for example, at least one selected from the group consisting of silicon (Si), silicon oxide (SiOx), silicon nitride (SiNx), and aluminum oxide (AlOx).
  • the silicon oxide includes, for example, at least one selected from the group consisting of glass and spin-on glass (SOG).
  • the metal material includes, for example, at least one selected from the group consisting of aluminum (Al), nickel (Ni), and stainless steel.
  • the polymer material includes, for example, at least one selected from the group consisting of polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethyletherketone (PEEK), and polyvinyl chloride (PVC).
  • a reflective layer (not shown) may be provided on at least one main surface of the base material 11 , or the base material 11 itself may have a function as a reflective layer. When the base material 11 has such a configuration, clearer color display is possible.
  • the recording layer 12 in an unrecorded state is in a decolored state.
  • the state of the recording layer 12 can be changed from the decolored state to a colored state by irradiation of laser light.
  • the recording layer 12 is capable of exhibiting a predetermined color in the colored state. Examples of the predetermined color include, but not limited to, black, cyan, magenta, yellow, red, green, and blue.
  • the thickness of the recording layer 12 is favorably 1 ⁇ m or more and 20 ⁇ m or less, more favorably 2 ⁇ m or more and 15 ⁇ m or less.
  • the thickness of the recording layer 12 is 1 ⁇ m or more, it is possible to achieve sufficient color density.
  • the thickness of the recording layer 12 is 20 ⁇ m or less, it is possible to prevent the heat utilization amount of the recording layer 12 from becoming too large. Therefore, it is possible to prevent the color development from deteriorating.
  • the recording layer 12 includes a coloring compound with electron-donating properties and a color developer with electron acceptability.
  • the recording layer 12 favorably further includes at least one selected from the group consisting of a photothermal conversion agent and a matrix resin.
  • the coloring compound is capable of developing color by reacting with a color developer.
  • the coloring compound is, for example, a leuco dye.
  • a lactone ring included in the molecule of the leuco dye reacts with a compound with electron acceptability such as an acid, the lactone ring opens to develop color.
  • the opened lactone ring in the leuco dye reacts with a base, it may be closed and may lose its color.
  • the leuco dye may be, for example, an existing dye for thermal paper.
  • the leuco dye may be, for example, an existing dye for thermal paper.
  • Specific examples of the leuco dye include a compound having a group with electron-donating properties in the molecule, which is represented by the following formula (2).
  • the coloring compound is not particularly limited and can be appropriately selected in accordance with the purpose.
  • Specific examples of the coloring compound include a fluorane compound, a triphenylmethanephthalide compound, an azaphthalide compound, a phenothiazine compound, a leuco auramine compound, and an indolinophthalide compound.
  • examples thereof include 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-di (n-butylamino) fluorane, 2-anilino-3-methyl-6-(N-n-propyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-isopropyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-isobutyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-n-amyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-sec-butyl-N-methylamino)fluorane, 2-anilino-3-methyl-6-(N-n-amyl-N-ethylamino)fluorane, 2-anilino-3-methyl-6-(N-iso)
  • the color developer is capable of, for example, causing a colorless coloring compound to develop color.
  • the color developer is a compound having a group with electron acceptability in the molecule. When the electron-accepting portion of the color developer reacts with a lactone ring of the coloring compound and the lactone ring opens, the coloring compound develops color.
  • the color developer includes a compound represented by the following formula (a).
  • X 0 when X 0 includes at least one benzene ring, since the melting point can be made higher than that in the case where X 0 represents an aliphatic hydrocarbon group (e.g., a normal alkyl chain), it is possible to improve color development retention characteristics during high-temperature and high-humidity preservation (hereinafter, referred to as “high-temperature and high-humidity preservation characteristics”.). From the viewpoint of improving high-temperature and high-humidity preservation characteristics and heat resistance, X 0 favorably has at least two benzene rings.
  • the high-temperature and high-humidity preservation characteristics are, for example, preservation characteristics in an environment of 80° C. and 60% RH.
  • the resistance of the recording medium 10 to harsh processes is improved.
  • the at least two benzene rings may be condensed.
  • naphthalene or anthracene may be obtained.
  • the color developers tend to solidify to some extent via hydrogen bonds.
  • the stability of the color developer in the recording layer 12 is improved.
  • the hydrogen-bonding group represents a functional group that contains an atom that can form a hydrogen bond with an atom in another functional group, another compound, or the like.
  • the color developer favorably includes a compound represented by the following formula (1).
  • X 1 when X 1 includes at least one benzene ring, since the melting point can be made higher than that in the case where X 1 represents an aliphatic hydrocarbon group (e.g., a normal alkyl chain), it is possible to improve high-temperature and high-humidity preservation characteristics. From the viewpoint of improving high-temperature and high-humidity preservation characteristics and heat resistance, X 1 favorably has at least two benzene rings. In the case where X 1 has at least two benzene rings, the at least two benzene rings may be condensed. For example, naphthalene or anthracene may be obtained.
  • the hydrocarbon group represents a general term for groups containing carbon (C) and hydrogen (H), and may be a saturated hydrocarbon group or an unsaturated hydrocarbon group.
  • the saturated hydrocarbon group is an aliphatic hydrocarbon group having no carbon-carbon multiple bond
  • the unsaturated hydrocarbon group is an aliphatic hydrocarbon group having a carbon-carbon multiple bond (a carbon-carbon double bond or a carbon-carbon triple bond).
  • the hydrocarbon group may be a chain one or include one or two or more rings.
  • the chain may be linear or branched having one or two or more side chains or the like.
  • X 0 in the formula (a) and X 1 in the formula (1) represent, for example, a divalent group having one benzene ring.
  • the divalent group is represented by, for example, the following formula (3).
  • the bonding sites of X 21 and X 22 to a benzene ring are not limited. That is, the bonding sites of X 21 and X 22 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • the above divalent group having one benzene ring is favorably represented by the following formula (4) from the viewpoint of improving high-temperature and high-humidity preservation characteristics.
  • the bonding sites of Z 01 and Z 02 to a benzene ring are not limited in the formula (4). That is, the bonding sites of Z 01 and Z 02 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • the bonding sites of Z 11 and Z 12 to a benzene ring are not limited in the formula (4). That is, the bonding sites of Z 11 and Z 12 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • X 21 and X 22 in the formula (3) only need to independently represent a divalent group and are not particularly limited.
  • Examples thereof include a hydrocarbon group, which may have a substituent group.
  • the hydrocarbon group is favorably a chain one.
  • the melting point of the color developer can be reduced.
  • the color developer melts by irradiation of laser light, making it easier for the coloring compound to develop color.
  • a normal alkyl chain, of the chain hydrocarbon groups is particularly favorable.
  • the number of carbons in the hydrocarbon group which may have a substituent group, is, for example, 1 or more and 15 or less, 1 or more and 13 or less, 1 or more and 12 or less, 1 or more and 10 or less, 1 or more and 6 or less, or 1 or more and 3 or less.
  • the number of carbons in the normal alkyl group is favorably 8 or less, more favorably 6 or less, still more favorably 5 or less, and particularly favorably 3 or less from the viewpoint of the high-temperature preservation stability.
  • the number of carbons in the normal alkyl group is 8 or less, since the length of the normal alkyl group is short, it is considerable that thermal disturbances are less likely to occur in the color developer during high-temperature preservation and the sites that have interacted with the coloring compound such as a leuco dye during color development become difficult to remove. Therefore, since the coloring compound such as a leuco dye becomes difficult to lose its color during high-temperature preservation, the high-temperature preservation stability is improved.
  • substituent group that the hydrocarbon group may have examples include a halogen group (e.g., a fluorine group) and an alkyl group having a halogen group (e.g., a fluorine group).
  • a halogen group e.g., a fluorine group
  • an alkyl group having a halogen group e.g., a fluorine group
  • some of the carbons in the hydrocarbon group are substituted with an element such as oxygen.
  • R 21 in the formula (3) only needs to represent a monovalent group and is not particularly limited. Examples thereof include a halogen group and a hydrocarbon group, which may have a substituent group.
  • the halogen group is, for example, a fluorine group (—F), a chlorine group (—Cl), a bromine group(—Br), or an iodine group (—I).
  • the carbons in the hydrocarbon group which may have a substituent group, is for example, 1 or more and 15 or less, 1 or more and 13 or less, 1 or more and 12 or less, 1 or more and 10 or less, 1 or more and 6 or less, or 1 or more and 3 or less.
  • substituent group that the hydrocarbon group may have examples include a halogen group (e.g., a fluorine group) and an alkyl group having a halogen group (e.g., a fluorine group).
  • a halogen group e.g., a fluorine group
  • an alkyl group having a halogen group e.g., a fluorine group
  • some of the carbons in the hydrocarbon group are substituted with an element such as oxygen.
  • R 22 in the formula (4) only needs to represent a monovalent group, and is not particularly limited. Examples thereof include a halogen group and a hydrocarbon group, which may have a substituent group.
  • the halogen group and the hydrocarbon group, which may have a substituent group, are similar to those in R 21 in the above formula (3).
  • X 0 in the formula (a) and X 1 in the formula (1) represent, for example, a divalent group having two benzene rings.
  • the divalent group is represented by, for example, the following formula (5).
  • the bonding sites of X 31 and X 32 to a benzene ring are not limited. That is, the bonding sites of X 31 and X 32 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • the bonding sites of X 32 and X 33 to a benzene ring are not limited. That is, the bonding sites of X 32 and X 33 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • the above divalent group having two benzene rings is favorably represented by the following formula (6) from the viewpoint of improving high-temperature and high-humidity preservation characteristics.
  • X 0 in the formula (a) represents a divalent group having two benzene rings
  • the bonding sites of Z 01 and X 34 to a benzene ring are not limited in the formula (6). That is, the bonding sites of Z 01 and X 34 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • the bonding sites of Z 02 and X 34 to a benzene ring are not limited. That is, the bonding sites of Z 02 and X 34 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • the bonding sites of Z 11 and X 34 to a benzene ring are not limited in the formula (6). That is, the bonding sites of Z 11 and X 34 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • the bonding sites of Z 12 and X 34 to a benzene ring are not limited. That is, the bonding sites of Z 12 and X 34 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • X 31 , X 32 , and X 33 in the formula (5) only need to independently represent a divalent group and are not particularly limited. Examples thereof include a hydrocarbon group, which may have a substituent group. The hydrocarbon group is similar to that in X 21 and X 22 in the above formula (3).
  • X 34 in the formula (6) only needs to represent a divalent group and is not particularly limited. Examples thereof include a hydrocarbon group, which may have a substituent group. The hydrocarbon group is similar to that in X 21 and X 22 in the above formula (3).
  • R 31 and R 32 in the formula (5) only need to represent a monovalent group, and are not particularly limited. Examples thereof include a halogen group and a hydrocarbon group, which may have a substituent group.
  • the halogen group and the hydrocarbon group, which may have a substituent group, are similar to those in R 21 in the above formula (3).
  • R 33 and R 34 in the formula (6) only need to represent a monovalent group, and are not particularly limited. Examples thereof include a halogen group and a hydrocarbon group, which may have a substituent group.
  • the halogen group and the hydrocarbon group, which may have a substituent group, are similar to those in R 21 in the above formula (3).
  • Y 01 and Y 02 in the formula (a) independently represent, for example, a hydrogen group (—H), a hydroxy group (—OH), a halogen group (—X), a carboxy group (—COOH), an ester group (—COOR), or a hydrocarbon group, which may have a substituent group.
  • the halogen group is, for example, a fluorine group (—F), a chlorine group (—Cl), a bromine group (—Br), or an iodine group (—I).
  • the number of carbons in the hydrocarbon group which may have a substituent group, is, for example, 1 or more and 15 or less, 1 or more and 13 or less, 1 or more and 12 or less, 1 or more and 10 or less, 1 or more and 6 or less, or 1 or more and 3 or less.
  • substituent group that the hydrocarbon group may have examples include a halogen group (e.g., a fluorine group) and an alkyl group having a halogen group (e.g., a fluorine group).
  • a halogen group e.g., a fluorine group
  • an alkyl group having a halogen group e.g., a fluorine group
  • some of the carbons in the hydrocarbon group are substituted with an element such as oxygen.
  • one of (Y 01 ) n01 and/or one of (Y 02 ) n02 favorably represents a hydroxy group (—OH).
  • one of (Y 01 ) n01 and/or one of (Y 02 ) n02 represents a hydroxy group (—OH)
  • the bonding sites of Y 11 and Y 12 to a benzene ring are not limited. That is, the bonding sites of Y 11 and Y 12 to a benzene ring may be any of an ortho portion, a meta position, and a para position.
  • the bonding sites of Y 13 and Y 14 to a benzene ring are also not limited. That is, the bonding sites of Y 13 and Y 14 to a benzene ring may also be any of an ortho portion, a meta position, and a para position.
  • the bonding sites of Y 11 and Y 12 to one benzene and the bonding sites of Y 13 and Y 14 to the other benzene may be the same or different.
  • Y 11 , Y 12 , Y 13 , and Y 14 in the formula (1) independently represent, for example, a hydrogen group (—H), a hydroxy group (—OH), a halogen group, a carboxy group (—COOH), an ester group (—COOR), or a hydrocarbon group, which may have a substituent group.
  • the halogen group and the hydrocarbon group, which may have a substituent group are similar to those in Y 01 and Y 02 in the above formula (a).
  • Y 11 and/or Y 13 favorably represents a hydroxy group (—OH).
  • Y 11 and/or Y 13 represents a hydroxy group (—OH)
  • Z 01 and Z 02 in the formula (1) independently represent, for example, a urea bond (—NHCONH—), an amide bond (—NHCO—, —OCHN—), or a hydrazide bond (—NHCOCONH—).
  • Z 01 and Z 02 favorably represent a urea bond.
  • Z 01 represents an amide bond
  • nitrogen contained in the amide bond may be bonded to benzene or carbon contained in the amide bond may be bonded to benzene.
  • Z 02 represents an amide bond
  • nitrogen contained in the amide bond may be bonded to benzene or carbon contained in the amide bond may be bonded to benzene.
  • Z 11 and Z 12 in the formula (1) independently represent, for example, a urea bond (—NHCONH—), an amide bond (—NHCO—, —OCHN—), or a hydrazide bond (—NHCOCONH—).
  • Z 11 and Z 12 favorably represent a urea bond.
  • Z 11 represents an amide bond
  • nitrogen contained in the amide bond may be bonded to benzene or carbon contained in the amide bond may be bonded to benzene.
  • Z 12 represents an amide bond
  • nitrogen contained in the amide bond may be bonded to benzene or carbon contained in the amide bond may be bonded to benzene.
  • a color developer in which X 0 in the formula (a) and X 1 in the formula (1) have one benzene ring specifically includes at least one selected from the group consisting of, for example, compounds represented by the following formulae (3-1) to (3-6).
  • a color developer in which X 0 in the formula (a) and X 1 in the formula (1) have two benzene rings specifically includes at least one selected from the group consisting of, for example, compounds represented by the following formulae (5-1) to (5-8).
  • the photothermal conversion agent is capable of absorbing light in a predetermined wavelength range such as a near-infrared region to generate heat.
  • a near-infrared absorbing dye that has an absorption peak in the wavelength range of 700 nm or more and 2000 nm or less and has substantially no absorption in the visible region.
  • Specific examples thereof include at least one selected from the group consisting of a compound having a phthalocyanine skeleton (phthalocyanine dye), a compound having a squarylium skeleton (squarylium dye), and an inorganic compound.
  • the inorganic compound examples include at least one selected from the group consisting of a metal complex such as a dithio complex, a diimonium salt, an aminium salt, graphite, carbon black, metal powder particles, tricobalt tetroxide, iron oxide, chromium oxide, copper oxide, titanium black, a metal oxide such as ITO (Indium Tin Oxide), a metal nitride such as niobium nitride, a metal carbide such as tantalum carbide, a metal sulfide, and various magnetic powders.
  • a compound having a cyanine skeleton, which has excellent light resistance and heat resistance, (cyanine dye) may be used.
  • the excellent light resistance means that it is not decomposed under the environment of use by irradiation of light such as light from a fluorescent light.
  • the excellent heat resistance means that, for example, the maximum absorption peak value of the absorption spectrum does not change by 20% or more when it is deposited with a polymer material and preserved at 150° C. for 30 minutes, for example.
  • Examples of such a compound having a cyanine skeleton include those having at least one of a counter ion of any of SbF 6 , PF 6 , BF 4 , ClO 4 , CF 3 SO 3 , and (CF 3 SO 3 ) 2 N and a methine chain having a 5-membered ring or a 6-membered ring in the molecule.
  • the compound having a cyanine skeleton used for the recording medium 10 favorably has both any of the above counter ions and a cyclic structure such as a 5-membered ring and a 6-membered ring in a methine chain, sufficient light resistance and heat resistance are ensured when the compound has at least one of them.
  • the matrix resin favorably has a function as a binder.
  • the matrix resin is favorably one in which the coloring compound, the color developer, and the photothermal conversion agent are easily and homogenously dispersed.
  • the matrix resin includes, for example, at least one selected from the group consisting of a thermosetting resin and a thermoplastic resin.
  • the matrix resin favorably includes a polycarbonate resin.
  • the polycarbonate resin is a resin having, as a structural unit, a carbonate group (—O—(C ⁇ O)—O—) at least in the main chain. Therefore, the main chain may have another structural unit in addition to the carbonate group.
  • the matrix resin may include, instead of or in addition to the polycarbonate resin, at least one selected from the group consisting of polyvinyl chloride, polyvinyl acetate, a vinyl chloride-vinyl acetate copolymer, ethylcellulose, polystyrene, a styrene copolymer, a phenoxy resin, a polyester, an aromatic polyester, polyurethane, polyacrylic acid ester, polymethacrylic acid ester, an acrylic acid copolymer, a maleic acid polymer, polyvinylalcohol, modified polyvinylalcohol, hydroxyethyl cellulose, carboxymethyl cellulose, and starch.
  • the recording layer 12 may further at least one additive selected from the group consisting of an antioxidant, a sensitizer, an ultraviolet absorber, a light stabilizer, and a hydrolysis inhibitor, as necessary. From the viewpoint of suppressing coloration of a background, the recording layer 12 favorably includes an amine compound.
  • the recording layer 12 favorably includes at least one compound selected from the group consisting of an epoxy compound and a carbodiimide compound, in addition to the amine compound.
  • the recording layer 12 includes at least one compound selected from the group consisting of an epoxy compound and a carbodiimide compound, in addition to the amine compound.
  • the protective layer 13 is for protecting the front surface of the recording layer 12 .
  • the protective layer 13 may have any of a single-layer structure and a multilayer structure.
  • the protective layer 13 having a single-layer structure may be a coat layer such as a hard coat layer.
  • the coat layer includes, for example, at least one cured product selected from the group consisting of a UV curable resin and a thermosetting resin.
  • the coat layer may include fine particles, or the like.
  • the protective layer having a multilayer structure may include a resin layer and a bonding layer provided on one surface of the resin layer. Note that the configuration of the thermal insulation layer having a multilayer structure is not limited to the above configuration.
  • the number of layers in the multilayer structure is not limited to the above two layers, and a structure having three or more layers may be adopted.
  • the resin layer may be a polymer film or a coat layer such as a UV curable resin layer.
  • the bonding layer is, for example, an adhesion layer or an adhesive layer.
  • the thickness of the protective layer 13 is, for example, 0.1 ⁇ m or more and 20 ⁇ m or less.
  • the photothermal conversion agent contained in the laser light irradiated portion of the recording layer 12 absorbs light and generates heat.
  • the color developer melts due to this heat generation, and a coloring reaction (color development reaction) occurs between the color developer and the coloring compound.
  • the color developer melts, the color developer reacts with a lactone ring of the coloring compound (e.g., a leuco dye), the lactone ring opens, and thus, the coloring compound develops color.
  • the laser light irradiated portion develops color and a desired image is drawn on the recording layer 12 .
  • the laser light it is favorable to use near-infrared laser light.
  • a matrix resin is dissolved in a solvent (e.g., methyl ethyl ketone).
  • a coloring compound in a decolored state, a color developer, and a photothermal conversion agent are added to this solution and dispersed.
  • a paint for forming a recording layer is obtained.
  • this paint for forming a recording layer is applied onto the base material 11 and dried to form the recording layer 12 .
  • the base material 11 and the recording layer 12 may be integrated by heat pressing as necessary.
  • a paint for forming a protective layer is applied onto the recording layer 12 and cured as necessary.
  • the paint for forming a protective layer includes, for example, at least one selected from the group consisting of a UV curable resin and a thermosetting resin. In this way, the recording medium 10 shown in FIG. 1 is obtained.
  • the color developer includes the compound represented by the above formula (a). Once the compound represented by the above formula (a) reacts with the coloring compound, it is difficult to separate. Further, since the color developers tend to solidify to some extent via hydrogen bonds, the stability of the color developer in the recording layer 12 is improved. Therefore, it is possible to improve high-temperature and high-humidity preservation characteristics of the recording medium 10 .
  • the compound represented by the above formula (a) does not easily interact with the coloring compound, it is possible to suppress color development of a background.
  • the reasons why the compound represented by the above formula (a) does not easily interact with the coloring compound are presumably because the melting point of the above compound is high, and due to steric hinderance or the like due to high aggregation ability between the above compounds, the type of terminal functional group of the above compound, and arrangement of functional groups of the above compound.
  • the recording medium 10 is capable of withstanding high-temperature pressing (e.g., high-temperature pressing at 150° C.).
  • “capable of withstanding” means that the color change due to high-temperature pressing can be suppressed.
  • X 0 in the formula (a) represents a divalent group that has at least one benzene ring and Z 11 and Z 12 in the formula (1) represent a urea bond (—NHCONH—)
  • Z 11 and Z 12 in the formula (1) represent a urea bond (—NHCONH—)
  • the melting point of the entire color developer can be made higher, it is possible to improve heat resistance of the recording medium 10 . Therefore, it is possible to improve the resistance of the recording medium 10 to harsh processes (e.g., hot pressing or integral molding using a molten resin). Therefore, the recording medium 10 can be included in various products(an identity card, a card, an accessory (including a wearable terminal), an electronic apparatus, and the like).
  • the recording layer 12 includes a polycarbonate resin as a matrix resin (matrix polymer)
  • the matrix resin is less likely to generate acid due to photolysis, and thus, it is possible to prevent the generated acid from reacting with the coloring compound. Therefore, it is possible to suppress the color development of the background (unrecorded area) of the recording medium 10 . Therefore, it is possible to improve the light resistance of the background of the recording medium 10 .
  • the matrix resin of the recording layer 12 includes a transparent polycarbonate resin. Since the polycarbonate resin itself has excellent transparency as well as the compounds represented by the above formula (a) and the above formula (1) have a benzene ring or the like in addition to a hydrogen bonding group in the molecule, the compatibility with the matrix resin is high. For this reason, it is easy to make the particle size small (e.g., 1 ⁇ m or less) during dispersion, and it is difficult to visually recognize during deposition. Therefore, it is improve the transparency of the recording layer 12 .
  • the polycarbonate resin itself has excellent transparency as well as the compounds represented by the above formula (a) and the above formula (1) have a benzene ring or the like in addition to a hydrogen bonding group in the molecule, the compatibility with the matrix resin is high. For this reason, it is easy to make the particle size small (e.g., 1 ⁇ m or less) during dispersion, and it is difficult to visually recognize during deposition. Therefore, it is improve the transparency of the recording
  • a recording medium includes one recording layer
  • a recording medium includes three recording layers having different color development hues in the colored state
  • the recording medium 10 A includes the base material 11 , three recording layers 12 A, 12 B, and 12 C, and two intermediate layers 14 A and 14 B.
  • the three recording layers 12 A, 12 B, and 12 C and the two intermediate layers 14 A and 14 B are stacked on the base material 11 in the order of the recording layer 12 A, the intermediate layer 14 A, the recording layer 12 B, the intermediate layer 14 B, and the recording layer 12 C.
  • the recording medium 10 A may further include the protective layer 13 on the recording layer 12 C.
  • the recording layers 12 A, 12 B, and 12 C in the unrecorded state are in the decolored state.
  • the state of each of the recording layers 12 A, 12 B, and 12 C can be changed from the decolored state to the colored state by irradiation of laser light.
  • the recording layers 12 A, 12 B, and 12 C are capable of exhibiting different hues in the colored state. Specifically, the recording layer 12 A is capable of exhibiting a magenta color in the colored state.
  • the recording layer 12 B is capable of exhibiting a cyan color in the colored state.
  • the recording layer 12 C is capable of exhibiting a yellow color in the colored state.
  • the magenta color, the cyan color, and the yellow color are respectively examples of a first color, a second color, and a third color.
  • the first color, the second color, and the third color may be colors other than the magenta color, the cyan color, and the yellow color.
  • the laser light capable of changing the state of the recording layer 12 A to the colored state, the laser light capable of changing the state of the recording layer 12 B to the colored state, and the laser light capable of changing the state of the recording layer 12 C to the colored state have different peak wavelengths.
  • the thickness of each of the recording layers 12 A, 12 B, and 12 C is favorably 1 ⁇ m or more and 20 ⁇ m or less, more favorably 2 ⁇ m or more and 15 ⁇ m or less.
  • the thickness of each of the recording layers 12 A, 12 B, and 12 C is 1 ⁇ m or more, it is possible to improve the color density.
  • the thickness of each of the recording layers 12 A, 12 B, and 12 C is 20 ⁇ m or less, it is possible to suppress the increase in heat utilization amount of the recording layers 12 A, 12 B, and 12 C and suppress deterioration of the color development.
  • the recording layer 12 A includes a first coloring compound with electron-donating properties, a first color developer with electron acceptability, and a first photothermal conversion agent.
  • the recording layer 12 A favorably further includes a first matrix resin.
  • the recording layer 12 B includes a second coloring compound with electron-donating properties, a second color developer with electron acceptability, and a second photothermal conversion agent.
  • the recording layer 12 B favorably further includes a second matrix resin.
  • the recording layer 12 C includes a third coloring compound with electron-donating properties, a third color developer with electron acceptability, and a third photothermal conversion agent.
  • the recording layer 12 C favorably further includes a third matrix resin.
  • the first, second, and third coloring compounds are capable of exhibiting different hues in the colored state.
  • the first coloring compound is capable of exhibiting a magenta color in the colored state.
  • the second coloring compound is capable of exhibiting a cyan color in the colored state.
  • the third coloring compound is capable of exhibiting a yellow color in the colored state.
  • the magenta color, the cyan color, and the yellow color are respectively examples of the first color, the second color, and the third color.
  • the first color, the second color, and the third color may be colors other than the magenta color, the cyan color, and the yellow color.
  • the first color developer is for causing the first coloring compound in the decolored state to develop color.
  • the second color developer is for causing the second coloring compound in the decolored state to develop color.
  • the third color developer is for causing the third coloring compound in the decolored state to develop color.
  • first, second, and third color developers those similar to the color developer included in the recording layer 12 according to the first embodiment can be used.
  • the types of first, second, and third color developers may be the same, or the types of first, second, and third color developers may be different from each other.
  • the first, second, and third photothermal conversion agents absorb light in a predetermined wavelength range such as a near-infrared region, and generate heat.
  • the first, second, and third photothermal conversion agents have different absorption wavelength peaks. Specifically, the first photothermal conversion agent has an absorption wavelength peak at a wavelength ⁇ 1 .
  • the second photothermal conversion agent has an absorption wavelength peak at a wavelength ⁇ 2 .
  • the third photothermal conversion agent has an absorption wavelength peak at a wavelength ⁇ 3 .
  • the wavelengths ⁇ 1 , ⁇ 2 , and ⁇ 3 are different from each other.
  • the absorption wavelength peak is favorably in a near-infrared region.
  • the near-infrared region is, for example, a wavelength range of 700 nm or more and 2000 nm or less. Since the first, second, and third photothermal conversion agents have different absorption wavelength peaks as described above, it is possible to selectively causing a desired layer of the recording layers 12 A, 12 B, and 12 C to develop color by irradiation of laser light. Examples of the first, second, and third photothermal conversion agents include those similar to the photothermal conversion agent included in the recording layer 12 according to the first embodiment.
  • first, second, and third matrix resins include those similar to the matrix resin included in the recording layer 12 according to the first embodiment.
  • the types of first, second, and third matrix resins may be the same, or the types of first, second, and third matrix resins may be different from each other.
  • the recording layers 12 A, 12 B, and 12 C may include an additive similar to that in the above recording layer 12 as necessary.
  • the intermediate layer 14 A is provided between the recording layer 12 A and the recording layer 12 B.
  • the intermediate layer 14 A is a thermal insulation layer capable of providing heat insulation between the recording layer 12 A and the recording layer 12 B.
  • the intermediate layer 14 B is provided between the recording layer 12 B and the recording layer 12 C.
  • the intermediate layer 14 B is a thermal insulation layer capable of providing heat insulation between the recording layer 12 B and the recording layer 12 C.
  • the intermediate layers 14 A and 14 B are each formed of, for example, a general polymer material having transparency.
  • the material include at least one selected from the group consisting of polyvinyl chloride, polyvinyl acetate, a vinyl chloride-vinyl acetate copolymer, ethylcellulose, polystyrene, a styrene copolymer, a phenoxy resin, a polyester, an aromatic polyester, polyurethane, polycarbonate, polyacrylic acid ester, polymethacrylic acid ester, an acrylic acid copolymer, a maleic acid polymer, polyvinylalcohol, modified polyvinylalcohol, hydroxyethyl cellulose, carboxymethyl cellulose, a silicone, polyethylene, polypropylene, and starch.
  • the intermediate layers 14 A and 14 B may each include, for example, various additives such as an ultraviolet absorber.
  • the intermediate layers 14 A and 14 B may each be formed of an inorganic material having transparency.
  • the intermediate layers 14 A and 14 B can be formed of, for example, a sol-gel method.
  • the thickness of each of the intermediate layers 14 A and 14 B is favorably 3 ⁇ m or more and 100 ⁇ m or less, more favorably 5 ⁇ m or more and 50 ⁇ m or less.
  • the thickness of each of the intermediate layers 14 A and 14 B is too small, there is a possibility that a sufficient heat insulation effect cannot be achieved.
  • the thickness of each of the intermediate layers 14 A and 14 B is too large, there is a possibility that the transparency decreases. Further, there is also a possibility that the bending resistance of the recording medium 10 B decreases and defects such as cracking easily occur.
  • the recording layer 12 A develops a magenta color as follows.
  • the first photothermal conversion agent contained in the laser light irradiated portion absorbs the near-infrared laser light and generates heat.
  • the first color developer melts due to this heat generation, a coloring reaction (color development reaction) occurs between the first color developer and the first coloring compound, and the laser light irradiated portion develops a magenta color.
  • the recording layer 12 B develops a cyan color as follows.
  • the laser light irradiated portion develops a cyan color by a reaction similar to that of the above recording layer 12 A.
  • the recording layer 12 C develops a yellow color as follows.
  • the laser light irradiated portion develops a yellow color by a reaction similar to that of the above recording layer 12 A.
  • the recording layers 12 A, 12 B, and 12 C are capable of respectively exhibiting a magenta color, a cyan color, and a yellow color in the colored state. Therefore, it is possible to draw a desired image in full color.
  • a recording medium includes three recording layers and a full-color image can be drawn has been described in the above second embodiment, an example in which a recording medium includes a recording layer including three types of microcapsules and a full-color image can be drawn will be described in a third embodiment.
  • the recording medium 10 B includes the base material 11 and a recording layer 15 provided on the base material 11 .
  • the recording medium 10 B may further include the protective layer 13 provided on the recording layer 15 . Note that in the third embodiment, portions similar to those in the first embodiment will be denoted by the same reference symbols and description thereof will be omitted.
  • the recording layer 15 includes three types of microcapsules 15 A, 15 B, and 15 C and a matrix resin.
  • the coloring state of each of the microcapsules 15 A, 15 B, and 15 C can be changed by irradiation of laser light.
  • the microcapsules 15 A, 15 B, and 15 C are capable of exhibiting different hues in the colored state. Specifically, the microcapsule 15 A is capable of exhibiting a magenta color in the colored state.
  • the microcapsule 15 B is capable of exhibiting a cyan color in the colored state.
  • the microcapsule 15 C is capable of exhibiting a yellow color in the colored state.
  • the magenta color, the cyan color, and the yellow color are respectively examples of the first color, the second color, and the third color.
  • the first color, the second color, and the third color may be colors other than the magenta color, the cyan color, and the yellow color.
  • the laser light capable of changing the state of the microcapsule 15 A to the colored state, the laser light capable of changing the state of the microcapsule 15 B to the colored state, and the laser light capable of changing the state of the microcapsule 15 C to the colored state have different peak wavelengths.
  • the microcapsule 15 A includes a first microcapsule wall, a first coloring compound with electron-donating properties, a first color developer with electron acceptability, and a first photothermal conversion agent.
  • the microcapsule 15 A may further include a first matrix resin.
  • the first microcapsule wall encapsulates the above various materials.
  • the microcapsule 15 B includes a second microcapsule wall, a second coloring compound with electron-donating properties, a second color developer with electron acceptability, and a second photothermal conversion agent.
  • the microcapsule 15 B may further include a second matrix resin.
  • the second microcapsule wall encapsulates the above various materials.
  • the microcapsule 15 C includes a third microcapsule wall, a third coloring compound with electron-donating properties, a third color developer with electron acceptability, and a third photothermal conversion agent.
  • the microcapsule 15 C may further include a third matrix resin.
  • the third microcapsule wall encapsulates the above various materials.
  • the first, second, and third microcapsule walls are each formed of, for example, a polymer material having transparency.
  • the material of the microcapsule wall include at least one selected from the group consisting of polyvinyl chloride, polyvinyl acetate, a vinyl chloride-vinyl acetate copolymer, ethylcellulose, polystyrene, a styrene copolymer, a phenoxy resin, a polyester, an aromatic polyester, polyurethane, polycarbonate, polyacrylic acid ester, polymethacrylic acid ester, an acrylic acid copolymer, a maleic acid polymer, polyvinylalcohol, modified polyvinylalcohol, hydroxyethyl cellulose, carboxymethyl cellulose, and starch.
  • the materials of the first, second, and third microcapsule walls may be the same, or the materials of the first, second, and third microcapsule walls may be different from each other.
  • the first, second, and third dyes with electron-donating properties are similar to those in the second embodiment.
  • the first, second, and third color developers are similar to those in the second embodiment.
  • the first, second, and third photothermal conversion agents are similar to those in the second embodiment.
  • the first, second, and third matrix resins are similar to those in the second embodiment.
  • the microcapsules 15 A, 15 B, and 15 C may include an additive similar to that in the above recording layer 12 as necessary.
  • the additive may be encapsulated in the first, second, and third microcapsule walls.
  • the recording layer 15 develops a magenta color as follows. A predetermined position of the recording layer 15 is irradiated with near-infrared laser light having the peak wavelength ⁇ 1 . The microcapsule 15 A contained in the laser light irradiated portion develops a magenta color. As a result, the laser light irradiated portion develops a magenta color.
  • the recording layer 15 develops a cyan color as follows. A predetermined position of the recording layer 15 is irradiated with near-infrared laser light having the peak wavelength ⁇ 2 . The microcapsule 15 B contained in the laser light irradiated portion develops a cyan color. As a result, the laser light irradiated portion develops a cyan color.
  • the recording layer 15 develops a yellow color as follows. A predetermined position of the recording layer 15 is irradiated with near-infrared laser light having the peak wavelength ⁇ 3 . The microcapsule 15 C contained in the laser light irradiated portion develops a yellow color. As a result, the laser light irradiated portion develops a yellow color.
  • the recording medium 10 B according to the third embodiment it is possible to achieve the operation and effect similar to those in the recording medium 10 according to the first embodiment.
  • the recording layer 15 includes three types of microcapsules 15 A, 15 B, and 15 C.
  • the microcapsules 15 A, 15 B, and 15 C are capable of respectively exhibiting a magenta color, a cyan color, and a yellow color in the colored state. Therefore, it is possible to draw a desired image in full color.
  • a stacked body that includes the recording medium 10 according to the first embodiment, the recording medium 10 A according to the second embodiment, or the recording medium 10 B according to the third embodiment will be described.
  • FIG. 4 is a perspective view showing an example of a configuration of a stacked body 20 according to the fourth embodiment.
  • FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4 .
  • the stacked body 20 includes a base material 21 , an adhesive layer 22 , an intermediate layer 23 , an adhesive layer 24 , an overlay layer 25 , and a recording medium 26 .
  • the stacked body 20 may be a card such as a security card, a financial payment card (e.g., a credit card or a cash card), an ID card (e.g., an employee ID card, a membership card, or a student ID card), and a personal transaction card (e.g., a prepaid card or a rewards card) (hereinafter, referred to as a “security card or the like”.).
  • a security card e.g., a credit card or a cash card
  • an ID card e.g., an employee ID card, a membership card, or a student ID card
  • a personal transaction card e.g., a prepaid card or a rewards card
  • the base material 21 is a support that supports the recording medium 26 and the intermediate layer 23 .
  • the base material 21 may be a card.
  • the base material 21 may have a color such as white.
  • a design, a picture, a photograph, a character, or a combination of two or more of them (hereinafter, referred to as a “design or the like”.) may be printed on one main surface of the base material 21 where the intermediate layer 23 , the recording medium 26 , and the like are provided.
  • the base material 21 includes, for example, plastic.
  • the base material 21 may include, as necessary, at least one selected from the group consisting of a coloring agent, an antistatic agent, a flame retardant, and a surface modifier.
  • the plastic includes, for example, at least one selected from the group consisting of an ester resin, an amide resin, an olefin resin, a vinyl resin, an acrylic resin, an imide resin, a styrene resin, and engineering plastic.
  • the base material 21 includes two or more types of resins, the two or more types of resins may be mixed, copolymerized, or stacked.
  • the ester resin includes, for example, at least one selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), a polyethylene terephthalate-isophthalate copolymer, and a terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer.
  • the amide resin includes, for example, at least one selected from the group consisting of nylon 6, nylon 66, and nylon 610.
  • the olefin resin includes, for example, at least one selected from the group consisting of polyethylene (PE), polypropylene (PP), and polymethylpentene (PMP).
  • the vinyl resin includes, for example, polyvinyl chloride (PVC).
  • the acrylic resin includes, for example, at least one selected from the group consisting of polyacrylate, polymethacrylate, and polymethylmethacrylate (PMMA).
  • the imide resin includes, for example, at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), and polyetherimide (PEI).
  • the styrene resin includes, for example, at least one selected from the group consisting of polystyrene (PS), high-impact polystyrene, an acrylonitrile-styrene resin (AS resin), and an acrylonitrile-butadiene-styrene resin (ABS resin).
  • the engineering plastic includes, for example, at least one selected from the group consisting of polycarbonate (PC), polyarylate (PAR), polysulfone (PSF), polyethersulfone (PES), polyphenyleneether (PPE), polyphenylene sulfide (PPS), polyetherketone (PEK), polyether-etherketone (PEEK), polyphenyleneoxide (PPO), and polyethersulfite.
  • PC polycarbonate
  • PAR polyarylate
  • PES polysulfone
  • PPE polyphenyleneether
  • PPS polyphenylene sulfide
  • PEK polyetherketone
  • PEEK polyether-etherketone
  • PPO polyphenyleneoxide
  • the intermediate layer 23 is provided on one main surface of the base material 21 , and the adhesive layer 22 is sandwiched between the base material 21 and the intermediate layer 23 .
  • the intermediate layer 23 includes a housing portion 23 A for housing the recording medium 26 .
  • the housing portion 23 A is provided in part of the plane of the intermediate layer 23 .
  • the housing portion 23 A may be a through hole penetrating the intermediate layer 23 in the thickness direction.
  • the intermediate layer 23 is for suppressing a step formed by the recording medium 26 when the recording medium 26 is sandwiched between the base material 21 and the overlay layer 25 .
  • the intermediate layer 23 has substantially the same thickness as that of the recording medium 26 , and covers a region of one main surface of the base material 21 other than the region where the recording medium 26 is provided.
  • the intermediate layer 23 has a film shape.
  • the intermediate layer 23 may have transparency.
  • the intermediate layer 23 includes plastic. Examples of the plastic include those similar to those of the base material 21 .
  • the overlay layer 25 is provided on the intermediate layer 23 and the recording medium 26 , and covers the intermediate layer 23 and the recording medium 26 .
  • the adhesive layer 24 is sandwiched between the intermediate layer 23 and the overlay layer 25 and between the recording medium 26 and the overlay layer 25 .
  • the overlay layer 25 protects the internal members of the stacked body 20 (i.e., the recording medium 26 and the intermediate layer 23 ), and maintains the mechanical reliability of the stacked body 20 .
  • the overlay layer 25 has a film shape.
  • the overlay layer 25 has transparency.
  • the overlay layer 25 includes plastic. Examples of the plastic include those similar to those of the base material 21 .
  • a design or the like may be printed on at least one main surface of the overlay layer 25 .
  • the adhesive layer 22 is provided between the base material 21 and the intermediate layer 23 , and bonds the base material 21 and the intermediate layer 23 together.
  • the adhesive layer 24 is provided between the intermediate layer 23 and the overlay layer 25 , and bonds the intermediate layer 23 and the overlay layer 25 together.
  • the adhesive layers 22 and 24 include a thermal adhesive.
  • the thermal adhesive includes a thermosetting resin.
  • the thermosetting resin includes, for example, at least one selected from the group consisting of an epoxy resin and a urethane resin. From the viewpoint of reducing damage to the recording medium 26 , the curing temperature of the thermal adhesive is favorably in the temperature range of 100° C. or more and 120° C. or less.
  • the recording medium 26 is the recording medium 10 according to the first embodiment, the recording medium 10 A according to the second embodiment, or the recording medium 10 B according to the third embodiment.
  • thermosetting resin is applied as a thermal adhesive onto one main surface of the base material 21 to form the adhesive layer 22 .
  • the recording medium 26 is fitted into the housing portion 23 A of the intermediate layer 23 .
  • the intermediate layer 23 in which the recording medium 26 is fitted into the housing portion 23 A in advance may be placed on the adhesive layer 22 .
  • the adhesive layer 22 may be formed by applying a thermosetting resin onto the intermediate layer 23 in which the recording medium 26 is fitted into the housing portion 23 A in advance and then placing the intermediate layer 23 on one main surface of the base material 21 so as to sandwich the coating film between them.
  • the adhesive layer 22 may be formed by bonding a sheet formed by applying a thermosetting resin to a separator in advance to the main surface of the base material 21 or the intermediate layer 23 in which the recording medium 26 is fitted into the housing portion 23 A in advance by means such as thermal lamination.
  • thermosetting resin is applied as a thermal adhesive onto the intermediate layer 23 to form the adhesive layer 24 , and then, the overlay layer 25 is placed on the adhesive layer 24 .
  • the obtained stacked body is sandwiched between metal plates and pressurized while heating to thermally cure the adhesive layer 22 and the adhesive layer 24 .
  • the temperature applied to the stacked body during thermal curing is favorably 100° C. or more and 120° C. or less.
  • the desired stacked body 20 is obtained.
  • the adhesive layer 24 may be formed by applying a thermosetting resin to the overlay layer 25 and placing the overlay layer 25 on the intermediate layer 23 so as to sandwich the coating film between them.
  • the adhesive layer 24 may be formed by bonding a sheet formed by applying a thermosetting resin to a separator in advance to the overlay layer 25 or the intermediate layer 23 by means such as thermal lamination.
  • the base material 21 and the intermediate layer 23 are bonded together by the adhesive layer 22 including a thermal adhesive
  • the intermediate layer 23 and the overlay layer 25 are bonded together by the adhesive layer 22 including a thermal adhesive.
  • the recording medium 26 is fitted into the housing portion 23 A of the intermediate layer 23 , it is possible to make it difficult to visually recognize the boundary between the recording medium 26 and the intermediate layer 23 in the in-plane direction of the stacked body 20 . Therefore, it becomes difficult to identify where in the plane of the stacked body 20 the recording medium 26 is provided. Therefore, it is possible to improve anti-tamper properties.
  • the recording medium 26 is enclosed within the stacked body 20 , it is possible to reduce the influence of exposure to water, a chemical substance, and the like on the recording medium 26 .
  • FIG. 6 is a cross-sectional view showing an example of a configuration of a stacked body 20 A according to the fifth embodiment.
  • the stacked body 20 A is different from the stacked body 20 according to the fourth embodiment in that it does not include the adhesive layer 22 and the adhesive layer 24 , the base material 21 and the intermediate layer 23 are bonded together by fusion, and the intermediate layer 23 and the overlay layer 25 are bonded together by fusion.
  • the base material 21 , the intermediate layer 23 , and the overlay layer 25 favorably include a thermoplastic resin as plastic.
  • the base material 21 , the intermediate layer 23 , and the overlay layer 25 include a thermoplastic resin, the interlayer adhesion strength by fusion can be enhanced.
  • the thermoplastic resin is favorably one capable of thermally fuse the layers of the stacked body 20 A in a temperature range of 130° C. or more and 200° C. or less.
  • the base material 21 , the intermediate layer 23 , and the overlay layer 25 may include the same type of thermoplastic resin, or the base material 21 , the intermediate layer 23 , and the overlay layer 25 do not necessarily need to include the same type of thermoplastic resin.
  • one layer of the base material 21 , the intermediate layer 23 , and the overlay layer 25 may include a thermoplastic resin of a type different from those of the other two layers, or the base material 21 , the intermediate layer 23 , and the overlay layer 25 may include different types of thermoplastic resins.
  • the base material 21 , the intermediate layer 23 , and the overlay layer 25 include the same type of thermoplastic resin
  • the base material 21 , the intermediate layer 23 , and the overlay layer 25 favorably include at least one selected from the group consisting of a semi-crystalline thermoplastic resin and an amorphous thermoplastic resin from the viewpoint of improving the interlayer adhesion strength by fusion.
  • the semi-crystalline thermoplastic resin includes, for example, at least one selected from the group consisting of polypropylene (PP), polyethylene (PE), polyacetal (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyetheretherketone (PEEK).
  • PP polypropylene
  • PE polyethylene
  • POM polyacetal
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PPS polyphenylene sulfide
  • PEEK polyetheretherketone
  • the amorphous thermoplastic resin includes, for example, at least one selected from the group consisting of an ABS resin, polycarbonate (PC), a polymer alloy of an ABS resin and PC (hereinafter, referred to as an “ABS/PC polymer alloy”.), an AS resin, polystyrene (PS), polymethylmethacrylate (PMMA), polyphenyleneoxide (PPO), polysulfone (PSU), polyvinyl chloride (PVC), polyetherimide (PEI), and polyethersulfone (PES).
  • an AS resin polystyrene (PS), polymethylmethacrylate (PMMA), polyphenyleneoxide (PPO), polysulfone (PSU), polyvinyl chloride (PVC), polyetherimide (PEI), and polyethersulfone (PES).
  • the base material 21 , the intermediate layer 23 , and the overlay layer 25 do not include the same type of thermoplastic resin
  • the base material 21 , the intermediate layer 23 , and the overlay layer 25 favorably include an amorphous thermoplastic resin from the viewpoint of improving the interlayer adhesion strength by fusion.
  • the following combinations are favorable as combinations of amorphous thermoplastic resins included in two adjacent layers of the stacked body 20 A.
  • the other layer favorably includes at least one selected from the group consisting of an ABS/PC polymer alloy, polycarbonate (PC), an AS resin, polystyrene (PS), polymethylmethacrylate (PMMA), and polyvinyl chloride (PVC).
  • the other layer favorably includes at least one selected from the group consisting of an ABS resin, polycarbonate (PC), and polymethylmethacrylate (PMMA).
  • the other layer favorably includes at least one selected from the group consisting of an ABS resin, an ABS/PC polymer alloy, and polymethylmethacrylate (PMMA).
  • the other layer favorably includes at least one selected from the group consisting of an ABS resin, polystyrene (PS), polymethylmethacrylate (PMMA), and polyphenyleneoxide (PPO).
  • PS polystyrene
  • PMMA polymethylmethacrylate
  • PPO polyphenyleneoxide
  • the other layer favorably includes at least one selected from the group consisting of an AS resin and polyphenyleneoxide (PPO).
  • the other layer favorably includes at least one selected from the group consisting of an ABS resin, an ABS/PC polymer alloy, an AS resin, and polyphenyleneoxide (PPO).
  • the other layer favorably includes at least one selected from the group consisting of polycarbonate (PC), an AS resin, polystyrene (PS), and polymethylmethacrylate (PMMA).
  • the other layer favorably includes polycarbonate (PC).
  • PC polycarbonate
  • the other layer favorably includes an ABS resin.
  • the intermediate layer 23 is placed on one main surface of the base material 21 , and then, the recording medium 26 is fitted into the housing portion 23 A of the intermediate layer 23 .
  • the intermediate layer 23 in which the recording medium 26 is fitted into the housing portion 23 A in advance may be placed on one main surface of the base material 21 .
  • the overlay layer 25 is placed on the intermediate layer 23 .
  • the obtained stacked body is sandwiched between metal plates and pressurized while heating to thermally fuse the base material 21 and the intermediate layer 23 and thermally fuse the intermediate layer 23 and the overlay layer 25 .
  • the temperature applied to the stacked body during thermal fusion is favorably 130° C. or more and 200° C. or less from the viewpoint of reducing damage to the recording medium 26 and exhibiting sufficient fusion strength. As a result, the desired stacked body 20 A is obtained.
  • the base material 21 and the intermediate layer 23 , and the intermediate layer 23 and the overlay layer 25 are fused. As a result, it is possible to firmly bond the base material 21 and the intermediate layer 23 together and firmly bond the intermediate layer 23 and the overlay layer 25 together. Therefore, it is possible to improve anti-tamper properties.
  • the intermediate layers 14 A and 14 B may be thermal insulation layers having a multilayer structure.
  • the thermal insulation layer having a multilayer structure may include a resin layer and a bonding layer provided on one main surface of the resin layer, or may include a resin layer and bonding layers provided on both surfaces of the resin layer.
  • the configuration of the thermal insulation layer having a multilayer structure is not limited to the above configuration.
  • the number of layers of the multilayer structure is also not limited to the above two layers and three layers, and a structure having four or more layers may be adopted.
  • the resin layer may be a polymer film or a coat layer such as a UV curable resin layer.
  • the bonding layer is, for example, an adhesion layer or an adhesive layer.
  • the bonding layer may be a double-sided adhesion film such as an OCA (Optical Clear Adhesive).
  • OCA Optical Clear Adhesive
  • the double-sided adhesion film may include only an adhesion layer, or may include a film as a base material, a first adhesion layer provided on a first surface of the film, and a second adhesion layer provided on a second surface of the film.
  • the recording medium 10 A may include a plurality of (other than three) recording layers and a plurality of (other than two) intermediate layers.
  • the plurality of recording layers and the plurality of intermediate layers may be stacked such that a recording layer and an intermediate layer are alternately located.
  • the plurality of recording layers may be capable of exhibiting different hues in the colored state. That is, the coloring compound included in each of the plurality of recording layers may be capable of exhibiting a different hue in the colored state.
  • the photothermal conversion agent included in each of the plurality of recording layers may have a different absorption wavelength peak.
  • the recording layer 15 includes the three types of microcapsules 15 A, 15 B, and 15 C
  • a plurality of (other than three) types of microcapsules may be included.
  • Each of the plurality of types of microcapsules may be capable of exhibiting a different view in the colored state. That is, the coloring compound included in the plurality of types of microcapsules may be capable of exhibiting a different hue in the colored state.
  • the photothermal conversion agent included in each of the plurality of types of microcapsules may have a different absorption wavelength peak.
  • the recording media 10 , 10 A, and 10 B include the base material 11 has been described in the first to third embodiments, respectively, the recording media 10 , 10 A, and 10 B do not necessarily need to include the base material 11 .
  • a UV cut layer may be provided between the recording layer 12 and the protective layer 13 .
  • UV cut layer UV light that enters the recording layer 12 can be cut, so that it is possible to prevent the recording layer 12 from deteriorating due to UV light.
  • a UV cut layer may be provided between the recording layer 12 C and the protective layer 13 .
  • a UV cut layer may be provided between the recording layer 15 and the protective layer 13 .
  • the upper limit value or the lower limit value in a numerical range at one stage may be replaced with the upper limit value or the lower limit value in a numerical range at another stage.
  • present disclosure may also take the following configurations.
  • the above recording media 10 , 10 A, and 10 B are applicable to various electronic apparatuses and some accessories, and the types of electronic apparatuses and accessories are not particularly limited. Specifically, for example, they are applicable to some of accessories such as a watch, a bag, clothes, a hat, glasses, and shoes as a wearable terminal. Further, they are applicable to not only electronic apparatuses and accessories but also, for example, an exterior member of an inner wall or outer wall of a building, and an exterior member of furniture such as a desk.
  • any of the recording media 10 A and 10 B can be applied to an identity card, a card, an electronic apparatus, and the like instead of the recording medium 10 , and two or more of the recording media 10 , 10 A, and 10 B can be combined and applied to an identity card, a card, an electronic apparatus, and the like.
  • an example in which a predetermined image is drawn on the recording medium 10 and a recorded area and an unrecorded area are formed in the recording layer 12 will be described.
  • Part A of FIG. 7 shows the appearance of a card-type identity card.
  • Part B of FIG. 7 is a cross-sectional view taken along the line VIIB-VIIB in Part A of FIG. 7 .
  • the card-type identity card is an example of a card or an identity card.
  • the card-type identity card includes a base material 31 , a bonding layer 32 , a recording medium 33 , a bonding layer 34 , and an overlay layer 35 in this order. Although an example in which the recording medium 33 is provided on one surface of the base material 31 will be described here, the recording medium 33 may be provided on both surfaces of the base material 31 .
  • the base material 31 is a support base material that supports the recording medium 33 .
  • the base material 31 is, for example, a plastic substrate.
  • the recording medium 33 is the recording medium 10 .
  • the bonding layer 32 bonds the base material 31 and the recording medium 33 to each other.
  • the bonding layer 34 bonds the recording medium 33 and the overlay layer 35 to each other.
  • the overlay layer 35 protects the recording medium 33 .
  • the overlay layer 35 covers one surface of the recording medium 33 .
  • card-type identity card examples include a driver's license, a health insurance card, a basic resident register card, and a personal number card (my number card).
  • FIG. 8 shows the appearance of a booklet-type identity card.
  • the booklet-type identity card is an example of a booklet.
  • the booklet-type identity card includes a plurality of sheets 41 .
  • the plurality of sheets 41 is saddle stitched.
  • the recording medium 10 is provided on at least one surface of the sheet 41 .
  • a character, a numerical value, a face photo, and the like are drawn on the recording medium 10 .
  • Specific examples of the booklet-type identity card include a passport.
  • Part A of FIG. 9 and Part B of FIG. 9 show the appearance of an integrated circuit (IC) card with a rewrite function.
  • the front surface of the card is a print surface 110
  • a sheet-shaped recording medium 10 is provided on the print surface 110 .
  • Part A of FIG. 10 and Part B of FIG. 10 show the appearance of a credit card with an IC chip.
  • the credit card with an IC chip is another example of the IC card.
  • the credit card includes an IC chip 121 on a front surface (first surface) 120 B, and a face photo 122 on a back surface (second surface) 120 A.
  • Part A of FIG. 11 shows an external configuration of a front surface of a smartphone.
  • Part B of FIG. 11 shows an external configuration of a back surface of the smartphone shown in Part A of FIG. 11 .
  • This smartphone includes, for example, a display portion 210 , a non-display portion 220 , and a casing 230 .
  • the recording medium 10 is provided as an exterior member of the casing 230 on, for example, one surface of the casing 230 on the back surface side. This makes it possible to display various color patterns as shown in Part B of FIG. 11 .
  • a smartphone has been taken as an example here, the present disclosure is not limited thereto and is applicable to, for example, a notebook personal computer (PC), a tablet PC, and the like.
  • Part A of FIG. 12 and Part B of FIG. 12 show the appearance of a bag.
  • This bag includes, for example, a compartment 310 and a handle 320 , and the recording medium 10 is provided in the compartment 310 .
  • the recording medium 10 is provided in the compartment 310 .
  • the design of the compartment 310 can be changed. It is possible to realize an electronic device that is useful also in fashion applications.
  • Part A of FIG. 13 shows the appearance of a top surface of an automobile
  • Part B of FIG. 13 shows the appearance of a side surface of the automobile.
  • FIG. 14 shows the appearance of a cosmetic container.
  • This cosmetic container includes a housing portion 510 and a lid 520 that covers the housing portion 510 , and the recording medium 10 is provided on the lid 520 .
  • This recording medium 10 decorates the lid 520 with, for example, a design shown in FIG. 14 , a color pattern, or a character.
  • the design of this lid 520 , color pattern, character, and the like can be written by a predetermined drawing device.
  • the recording medium 10 can be attached to not only the front surface (lid 520 ) of the cosmetic container but also the back surface (housing portion 510 ) or the like.
  • FIG. 15 shows the appearance of a nail tip.
  • the nail tip is an example of an exterior member.
  • the nail tip includes the recording medium 10 on the front surface.
  • the configuration of the nail tip is not limited thereto and the recording medium 10 itself may be a nail tip.
  • the base material 11 has a nail shape.
  • Part A of FIG. 16 shows the appearance of a nail sticker.
  • Part B of FIG. 16 shows the cross section taken along the line XVIB-XVIB in Part A of FIG. 16 .
  • the nail sticker is an example of an exterior member.
  • the nail sticker includes a recording medium with an adhesive layer 610 and a release sheet 620 .
  • the recording medium with an adhesive layer 610 includes the recording medium 10 and an adhesion layer 611 .
  • the adhesion layer 611 is provided on the surface of the recording medium 10 on the side of the base material 11 .
  • the recording medium 10 may further include the protective layer 13 on the recording layer 12 .
  • the recording medium 10 and the like include a plurality of nail sticker portions 612 to be attached to the nails of fingers of both hands.
  • the nail sticker portion 612 is held in a cut or half-cut state relative to the nail sticker and is configured to be peelable on the interface between the adhesion layer 611 and the release sheet 620 .
  • the recording layer 12 may be directly formed on a bare nail (human nail) as a support base material.
  • the recording layer 12 may be formed by applying a paint to the bare nail and curing it, or the recording layer 12 having self-supporting properties may be separately formed and attached to the bare nail.
  • PC polycarbonate
  • MEK methyl ethyl ketone
  • a color developer was added thereto, and the mixture was dispersed using a rocking mill.
  • different color developers compounds represented by the formulae (2A) to (10A)
  • a photothermal conversion material having a phthalocyanine skeleton was added to prepare a paint for forming a recording layer. Note that the mixing amount of the photothermal conversion material was such that the absorbance during coating was 0.32.
  • a paint for forming a recording layer was applied onto a PET (support base) having a thickness of 50 ⁇ m using a wire bar, and dried at 110° C. for 5 minutes to obtain a recording layer.
  • the conditions for applying the paint for forming a recording layer were adjusted such that the film thickness of the dried recording layer was the value shown in Table 1.
  • a colored portion and an uncolored portion were formed. In this way, a desired recording medium was obtained.
  • a recording medium was obtained in a way similar to that in Example 2 except that a leuco dye that exhibits a yellow color in the colored state was mixed as a leuco dye in the process of preparing a paint for forming a recording layer.
  • a recording medium was obtained in a way similar to that in Example 2 except that a leuco dye that exhibits a cyan color in the colored state was mixed as a leuco dye in the process of preparing a paint for forming a recording layer.
  • a recording medium was obtained in a way similar to that in Example 11 except that a light stabilizer (Hostavin N-30 manufactured by Clariant) was further mixed in the paint for forming a recording layer in the process of preparing a paint for forming a recording layer.
  • the mixing amount of the light stabilizer was set to 1.4 parts by mass with respect to 100 parts by mass of the total amount of the leuco dye, the color developer, polycarbonate, the photothermal conversion material, and the light stabilizer.
  • a recording medium was obtained in a way similar to that in Example 2 except that polyvinyl chloride-vinyl acetate copolymer (PVC) was mixed as a matrix resin instead of polycarbonate (PC) in the process of preparing a paint for forming a recording layer.
  • PVC polyvinyl chloride-vinyl acetate copolymer
  • the recording media obtained as described above were evaluated as follows.
  • the OD of the colored portion of the recording medium was measured three times at the same position in a standard environment (23° C., 50 RH %), and the measured values were simply averaged (arithmetically averaged) to obtain the average OD of the colored portion.
  • the ODs of C (cyan), M (magenta), and Y (yellow) corresponding to the visually recognized colors were used as the ODs of the respective colors.
  • the average OD of the uncolored portion (background) of the recording medium was obtained in a way similar to that for the average OD of the colored portion of the recording medium.
  • the conditions for measuring OD are as follows.
  • the average OD of the colored portion and the average OD of the uncolored portion were respectively converted into the average OD of the colored portion in the recording layer having a film thickness of 5 ⁇ m and the average OD of the uncolored portion in the recording layer having a film thickness of 5 ⁇ m.
  • Table 1 shows the average OD of the colored portion before and after conversion, and the average OD of the uncolored portion before and after conversion.
  • Evaluation 2 The average OD of the uncolored portion (unrecorded area) after conversion is 0.30 or less.
  • Evaluation 1 The average OD of the uncolored portion (unrecorded area) after conversion exceeds 0.30.
  • the reference value for determination in the two-stage evaluation was set to 0.30 of the average OD of the uncolored portion (unrecorded area) after conversion.
  • a preservation test was conducted by preserving the recording medium under high-temperature and low-humidity conditions of 80° C. and 30% RH for 200 hours.
  • the condition of the temperature of 80° C. in the preservation test is the highest temperature in the preservation test for all parts. If a good result is obtained in the preservation test at this temperature, the recording medium is presumably capable of withstanding preservation under various environments.
  • the average OD of the colored portion in the recording layer having a film thickness of 5 ⁇ m was obtained in a way similar to that for the above “evaluation of OD in standard environment”.
  • the OD maintenance rate of the colored portion before and after the preservation test was obtained using the following formula.
  • the average OD of the colored portion before the preservation test the average OD of the colored portion in the recording layer having a film thickness of 5 ⁇ m, which was obtained in the above “Evaluation of OD in standard environment”, was used.
  • Evaluation 2 The OD maintenance rate of the colored portion before and after the preservation test is 85% or more.
  • Evaluation 1 The OD maintenance rate of the colored portion before and after the preservation test is less than 85%.
  • the reference value for determination in the two-stage evaluation was set to 85% of the OD maintenance rate.
  • the OD maintenance rate of the colored portion before and after the preservation test was obtained in a way similar that in the above “Evaluation of preservation stability in high-temperature and low-humidity environment” except that the preservation test was conducted by preserving the recording medium under high-temperature and high-humidity conditions of 80° C. and 60% RH for 200 hours. Subsequently, the preservation stability was evaluated in two stages in a way similar to that in the above “Evaluation of preservation stability in high-temperature and low-humidity environment”. The evaluation results are shown in Table 1.
  • an unheated recording medium was prepared and used as a sample A.
  • L*, a*, and b* of the uncolored portion of the sample A were measured three times at the same position in a standard environment (23° C., 50 RH %), and the measured values were simply averaged (arithmetically averaged) to obtain an average L*, an average a*, and an average b* of the uncolored portion (hereinafter, referred to as “L 0 *, a 0 *, and b 0 *”.).
  • an unheated recording medium was placed in an oven (manufactured by AS ONE Corporation, ETTAS vacuum dryer AVO-250V) heated to 150° C. in advance for 30 minutes and used as a sample B.
  • L*, a*, and b* of the uncolored portion of the sample B were measured three times at the same position, and the measured values were simply averaged (arithmetically averaged) to obtain an average *, an average a*, and an average b* of the uncolored portion (hereinafter, referred to as “L 1 *, a 1 *, and b 1 *”.).
  • the measurement conditions for L*, a*, and b* are as follows.
  • Measuring apparatus Spectrophotometer (Xrite eXact manufactured by X-Rite, Incorporated)
  • ⁇ E ab * ⁇ 3.2 means that ⁇ E ab * is a class A tolerance or smaller than that.
  • the class A tolerance means a color difference level that is hardly noticeable in color separation comparisons, i.e., a level at which the color is generally considered to be the same color.
  • ⁇ E ab * is a class B tolerance.
  • the class B tolerance means a range that can be treated as the same color at an impression level.
  • 6.5 ⁇ E ab * means that ⁇ E ab * is a class C tolerance or larger than that.
  • the class C tolerance means a color difference corresponding to one step in JIS standard color chart, Munsell color chart, or the like.
  • a UV cut barrier was formed on the recording layer of each of the recording media according to Examples 2 and 13 obtained as described above and then the average OD of each of the colored portion the uncolored portion was obtained.
  • an accelerated light resistance test (test conditions: irradiance of 60 W/m 2 , black panel temperature of 63° C., irradiation time of 200 hours, and filter: direct sunlight filter (Daylight-Q)) was conducted on the recording medium using a xenon arc tester (manufactured by Q-Lab Corporation, Q-SUN Xe-1), and then the average OD of each of the colored portion and the uncolored portion of the recording medium was obtained again.
  • the OD maintenance rate before and after the light resistance test was obtained using the following formula.
  • Evaluation 2 The OD maintenance rate of the colored portion before and after the light resistance test is 85% or more.
  • Evaluation 1 The OD maintenance rate of the colored portion before and after the light resistance test is less than 85%.
  • the reference value for determination in the two-stage evaluation was set to 85% of the OD maintenance rate.
  • Evaluation 1 The OD maintenance rate of the colored portion before and after the light resistance test is larger than 115%.
  • the reference value for determination in the two-stage evaluation was set to 115% of the OD maintenance rate.
  • the Evaluation Result of the OD Maintenance rate is larger than 95%.
  • the evaluation result of the OD maintenance rate is larger than 85% and 95% or less.
  • the evaluation result of the OD maintenance rate is less than 50%.
  • the evaluation result of the OD maintenance rate is larger than 120%.
  • the evaluation result of the OD maintenance rate is larger than 95% and 120 or less.
  • the recording layer includes the compound represented by the formula (1) as a color developer, it is possible to improve both high-temperature and low-humidity preservation characteristics and high-temperature and high-humidity preservation characteristics and suppress coloration of a background. Further, it is also possible to improve heat resistance.
  • the recording layer includes polycarbonate as a matrix resin, it is possible to improve the light resistance of the background of the recording medium.

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